The CH2MHill report was ordered by Mayor Steve Bach, who was alarmed that the city’s stormwater backlog costs apparently rose from $500 million in 2009 to almost $688 million in last year’s estimate by a stormwater task force.

The new amount was about $535 million.

The engineers started by looking at a list of 282 projects within Colorado Springs, as well as reviewing stormwater documents going back 40 years, project manager Mark Rosser explained.

Those projects were part of the task force’s larger study that identified $850 million in backlog for all of El Paso County, as well as nearly $11 million in operation and maintenance needs.

The consultants removed 44 projects that had been constructed, duplicated or that no longer existed. One of those was a $138 million project to replace all corrugated metal pipe drains in the city.

The remaining projects were rated according to urgency, and in some cases broken out into multiple projects.

“We were dealing with long reaches of streams,” Rosser said.

From that list of 239 projects, about 44 were given high priority, with a total cost of $162 million — more than twice the amount critical projects were estimated at in 2009.

The longer Colorado Springs waits to begin addressing projects, the worse things will get, he added.

“The work doesn’t consider what happened in September and October.”

CH2MHill is working on a similar estimate for El Paso County, expected to be completed in December.